To gain an understanding of the function of specific genes, simple model systems often have the advantage that the gene has fewer functions and the gene family of which it is a member has fewer members, thereby minimizing redundancy. One approach is to use a system in which the developing tissues and regions can be manipulated in a variety of ways resulting in alterations of the expression and activity of an introduced transgene leading to a clearer and/or more detailed understanding of the role of the gene. Hydra, a cnidarian, is particularly useful for this approach to studying gene function. The animal has a simple body plan with few cell types. The processes governing pattern formation, cell fate decisions, and tissue growth are well understood at a tissue and cell level, These processes are constantly active in the adult hydra due to the tissue dynamics of the adult. The adult animal is amenable to a variety of manipulations which are useful for exploring the role of a particular gene. Many genes which regulate these developmental processes in more complex organisms have been isolated from hydra. For most of these genes the expression patterns are simple. For a number of these genes, their normal patterns coupled with alterations in expression due to tissue manipulations indicate they have functions analogous to their homologues in vertebrates. The focus of this proposal will be the generation of transgenic hydra. Two approaches will be tried towards stably introducing transgenes into the hydra genome. One makes use of two different retroviruses, each with a vsv-g coat protein that permits infection of a wide variety of organisms from amoeba to mammals. Initial experiments indicate that when hydra embryos at the blastula stage are injected, a small fraction of the resulting hatchlings contain the viral genome suggesting stable integration. The second approach will involve use of a transposable elements with a broad host range specificity [amoeba to insects]. Should either or both of these approaches work, efforts will be focused on optimizing the procedure for introducing the transgenes.